1. Field of the Invention
The present invention relates to an optical device, and more particularly, to a temperature-insensitive polymeric optical arrayed waveguide grating (AWG) device having an optical characteristic that does not vary with a temperature variation due to a lower structure and a method of manufacturing the same.
2. Description of the Related Art
Wavelength division multiplexing (WDM) systems are used to transmit a large amount of information. Examples of optical devices widely used in optical communications include optical planar waveguides, AWG devices, and the like. In particular, a technology for using polymeric AWG devices with MUX/DeMUX in WDM optical communications has attracted much interest.
Polymeric optical devices are more easily manufactured than silica optical devices and thus have attracted attention for use in optical communications. Nevertheless, the application range of polymeric optical devices is considerably restricted due to the relatively greater temperature dependence than silica optical devices.
For example, in the case of a silica AWG device, a variation of a central wavelength with a temperature is about 0.01 nm/° C. However, in the case of a polymeric AWG device, although a variation of a central wavelength with a temperature depends on the type of a polymeric material, the variation is generally about −0.1 nm/° C. Thus, it may be estimated that the temperature dependence of the polymeric AWG device is 10 times higher that of the silica AWG device.
Various methods of improving the temperature dependence of such AWG devices have been proposed. Also, various studies for effectively reducing the temperature dependence of polymeric optical devices and polymeric AWG devices used as a MUX/DeMUX in WDM communications have been performed.
For example, a method of changing a material of a substrate under a waveguide or adding a new layer having a different thermal expansion coefficient has been considered. A substrate having an appropriate characteristic must be found to reduce the temperature dependence. Also, in the case where the thermal expansion coefficient of a polymer constituting a waveguide is greatly different from a thermal expansion coefficient of the substrate, the substrate may be bent during a subsequent manufacturing process.
Accordingly, a method of effectively reducing the temperature dependence of a polymeric waveguide is required. In particular, a method of reducing the temperature dependence of a polymeric AWG device used as a MUX/DeMUX in temperature-sensitive WDM optical communications is required.